1. Field of the Invention
The present invention relates to a water-saving type shower head which is operable to reduce flow volume while maintaining a high discharge pressure of water discharged from the shower head.
2. Description of the Related Prior Art
A conventional shower head has a shower head body and a sprinkler plate which is provided with a number of small holes and disposed in a distal portion of the shower head body. The conventional shower head uses pressure of water (including mixed hot and cold water) supplied from a proximal side of the shower head to discharge water from the sprinkler plate. Accordingly, strength of the water discharged from the sprinkler plate, i.e. speed of the water spurt from the small holes in the plate, depends on water pressure inside the shower head body. If the water has pressure within a range of standard values of normal tap water pressure, the water is showered at sufficient speed. However, if the tap water pressure is decreased due to enforcement of water restriction etc., power of the discharged water is extremely reduced. Moreover, if a faucet to which the shower head is connected is turned down to save water, the pressure inside the shower head body is lowered, which extremely weakens strength of the water discharged from the sprinkler plate.
In view of the above circumstances, Japanese Patent Gazette No. 2670509 proposes a water-saving type shower head in which a flow control member having a diameter-reduced water passage portion is provided on an upstream side of a sprinkler plate. The diameter-reduced water passage portion of the water-saving type shower head has a tapered diameter-reduced portion reduced in diameter in a flow direction and a diameter-increased portion increased in diameter in the flow direction which are disposed on an entry side and an exit side of the diameter-reduced water passage portion, respectively. Water is accelerated when passing through the diameter-reduced water passage portion. Moreover, the exit side of the diameter-reduced water passage portion is increased in diameter. Accordingly, the accelerated water is impinged on the sprinkler plate having a relatively large area without decreasing kinetic energy of the water.
Although the invention of Japanese Patent Gazette No. 2670509 is capable of enhancing discharge pressure of the water discharged from the sprinkler plate of the shower head, flow volume of the discharged water is high because the diameter-reduced water passage portion has a large diameter. This brings about a problem that shower water hits a user's skin hard and gives slight pain when the shower is used. If the diameter of the diameter-reduced water passage portion is simply reduced to solve the problem, passage resistance of water is increased, which not only decreases flow volume of water but also generates pressure loss in water flow. This brings about another problem that shower water having prescribed force cannot be obtained.